Well, last night, some weeks after asking this question as the OP, I picked up the E2D LED Defender after by chance walking past a store with a banner that said, "Surefire Dealer."
At first use of the Defender, it is clear that the LX2 is just a nicer light in terms of feel and finish and the price diff is accounted for in my mind anyway. In fact, if I didn't need the "clickie" feature of the Defender for traffic stops, the LX2 would be my only light. Both Surefire's are superior at car illumination than my larger duty lights because of their broader beams although lumens are all in the same ball park.
Well, it's gotten a little out of hand. Now with an LX2, 2 Defenders (one of the 2 still on order), a Polystinger (being repaired), and a Pelican 7060 I am definitely done with lights unless the technology shifts dramatically.